Electronic control system for an internal combustion engine with correction means for correcting value determined by the control system with reference to atmospheric air pressure

Abstract

An electronic engine control system has a pressure sensor communicating both to the intake manifold and the ambient air via a valve means selectively introducing either the intake vacuum or the ambient air into the pressure sensor. The control system further includes a valve control means for controlling the operation of the valve means for selectively communicating the pressure sensor to the intake manifold and the ambient air. The valve control means is incorporated in a controller for determining the control value and adapted to produce a control signal to be supplied to the valve means in order to electrically control the valve motion.

What is claimed is: 
     
       1. An electronic control system for an internal combustion engine for controlling the engine operation based on at least an intake vacuum pressure of the engine and an atmospheric air pressure comprising: a pressure sensor for measuring a pressure introduced;   switching means for selectively introducing an intake vacuum pressure and an atmospheric air pressure into said pressure sensor;   signal generating means for producing a signal for switching over said switching means; and   a control unit for receiving a pressure signal from said pressure sensor and producing a control signal for controlling the engine operation.   
     
     
       2. An electronic control system for an internal combustion engine for controlling the engine operation based on various engine control parameters comprising: an engine speed sensor for determining the engine revolution speed and producing an engine speed signal representative of the determined engine speed;   engine temperature sensor for determining the engine temperature and producing an engine temperature signal representative of the determined engine temperature;   engine load sensor for determining the load conditions of the engine, said engine load sensor including a pressure sensor for determining a pressure introduced;   switching means associated with said pressure sensor for selectively introducing vacuum pressure and an atmospheric pressure into said pressure sensor;   a control unit for controlling fuel supply, spark ignition and exhaust gas recirculation, said control unit determining control values for controlling engine operation on the basis of the sensor signals fed from the engine speed sensor, engine temperature sensor and engine load sensor; and   switch signal generating means, incorporated within said control unit and associated with said switching means, for producing a switching signal for controlling switching over said switching means.   
     
     
       3. The system as set forth in claim 1 or 2, wherein said switching means comprises a flow control valve assembly including a valve housing having first inlet port communicating with the intake manifold, second inlet port communicating with the ambient air, and an outlet port communicating with said pressure sensor, a valve member disposed within said valve housing and being movable between a first position wherein said first inlet port communicates with said outlet port and second position where said second port communicates with said outlet port, and an actuator for moving said valve member between said first and second position, said actuator being responsive to said signal supplied from the signal generating means. 
     
     
       4. The system as set forth in claim 3, wherein said signal generating means produces the signal to be supplied to said switching means in synchronism with the engine revolution. 
     
     
       5. The system as set forth in claim 3, wherein said control unit comprises a multiplexer, an arithmetic circuit, and an output unit, said multiplexer being responsive to said signal supplied from said signal generating means for selectively inputting the sensor signal to said arithmetic circuit. 
     
     
       6. A method for controlling an internal combustion engine comprising; detecting engine operating conditions including detecting engine intake vacuum and atmospheric air pressure alternatively at a given timing by selectively applying said engine vacuum and said atmospheric air pressure to a sensor;   determining a basic fuel amount to be supplied to the engine combustion chamber based on detected engine operating conditions including said intake vacuum;   correcting said basic fuel amount by a correction value determined according to said atmospheric air pressure to produce a fuel amount control signal; and   controlling the fuel amount actually supplied to the engine cylinder in response to the fuel amount control signal.   
     
     
       7. The method as set forth in claim 6, wherein said method further comprises: determining air/fuel ratio based on the oxygen concentration in the exhaust gas;   determining spark ignition timing based on the determined air/fuel ratio according to the atmospheric air pressure.   
     
     
       8. The method as set forth in claim 6 or 7, wherein said method further comprises: determining a basic value of exhaust gas recirculation rate for recirculating the exhaust gas into the engine cylinder; and   correcting the determined basic exhaust gas recirculation rate depending on a correction value determined according to atmospheric air pressure.   
     
     
       9. An electronic control system for an internal combustion engine for controlling engine operation based on at least an intake vacuum pressure of the engine and an atmospheric air pressure comprising: a pressure sensor for measuring a pressure introduced and producing a pressure signal representative of said pressure introduced;   switching means, associated with said pressure sensor, for selectively introducing an intake vacuum pressure and an atmospheric air pressure into said pressure sensor, said switching means periodically switching introducing of said intake vacuum pressure and said atmospheric pressure to said pressure sensor at a given timing; and   a control unit for receiving said pressure signal from said pressure sensor and producing a control signal for controlling the engine operation.   
     
     
       10. An electronic control system for an internal combustion engine for controlling engine operation based on various engine control parameters comprising: an engine speed sensor for determining engine revolution speed and producing an engine speed signal representative of the determined engine speed;   an engine temperature sensor for determining engine temperature and producing an engine temperature signal representative of the determined engine temperature;   an engine load sensor for determining load conditions of the engine, said engine load sensor including a pressure sensor for determining a pressure introduced and producing a pressure signal representative of said pressure introduced;   switching means associated with said pressure sensor for selectively introducing vacuum pressure and an atmospheric pressure into said pressure sensor, said switching means being operative at a given timing for changing over introduction of said intake pressure and said atmospheric pressure; and   a control unit for controlling fuel supply, spark ignition and exhaust gas recirculation, said control unit determining control values for controlling engine operation on the basis of the signals produced by the engine speed sensor, engine temperature sensor and engine load sensor.   
     
     
       11. An electronic control system for an internal combustion engine for controlling engine operation based on at least an intake vacuum pressure of the engine and an atmospheric air pressure comprising: a pressure sensor for measuring a pressure introduced and producing a pressure signal representative of said pressure introduced;   switching means, associated with said pressure sensor, for selectively introducing an intake vacuum pressure and an atmospheric air pressure into said pressure sensor; and   a control unit, associated with said switching means to produce a periodic signal for operating said switching means for switching introduction of said intake vacuum pressure and said atmospheric pressure at a given timing, said control unit receiving said pressure signal from said pressure sensor and producing a control signal for controlling the engine operation.   
     
     
       12. An electronic control system for an internal combustion engine for controlling engine operation based on various engine control parameters comprising: an engine speed sensor for determining the engine revolution speed and producing an engine speed signal representative of the determined engine speed;   engine temperature sensor for determining the engine temperature and producing an engine temperature signal representative of the determined engine temperature;   engine load sensor for determining the load conditions of the engine, said engine load sensor including a pressure sensor for determining a pressure introduced and producing a pressure signal representative of said pressure introduced;   switching means associated with said pressure sensor for selectively introducing vacuum pressure and an atmospheric pressure into said pressure sensor; and   a control unit associated with said switching means to produce a periodic signal for operating said switching means at a given timing, said control unit controlling fuel supply, spark ignition and exhaust gas recirculation, said control unit determining control values for controlling engine operation on the basis of the signals produced by the engine speed sensor, engine temperature sensor and engine load sensor.   
     
     
       13. The system as set forth in claim 9 or 10, wherein said switching means comprises a flow control valve assembly including a valve housing having a first inlet port communicating with an intake manifold, a second inlet port communicating with atmospheric pressure, and an outlet port communicating with said pressure sensor, a valve member disposed within said valve housing and being movable between a first position wherein said first inlet port communicates with said outlet port and second position where said second inlet port communicates with said outlet port, and an actuator for moving said valve member between said first and second positions, and switching signal generating means associated with said switching means for supplying a signal to said switching means for controlling said actuator to move said valve member. 
     
     
       14. The system as set forth in claim 13, wherein said control unit comprises a multiplexer connected to receive said sensor signals, an arithmetic circuit, and an output unit, said multiplexer being responsive to said signal supplied from said switching signal generating means for selectively inputting said sensor signals to said arithmetic circuit. 
     
     
       15. The system as set forth in claim 11 or 12, wherein said switching means comprises a flow control valve assembly including a valve housing having a first inlet port communicating with an intake manifold, a second inlet port communicating with ambient air, and an outlet port communicating with said pressure sensor, a valve member disposed within said valve housing and being movable between a first position wherein said first inlet port communicates with said outlet port and second position where said second inlet port communicates with said outlet port and an actuator for moving said valve member between said first and second positions, said control unit including switch signal generating means for producing said signal for operating said switching means and said actuator being responsive to said signal from the switching signal generating means. 
     
     
       16. The system as set forth in claim 15, wherein said control unit comprises a multiplexer connected to receive said sensor signals, an arithmetic circuit, and an output unit, said multiplexer being responsive to said signal supplied from said switching signal generating means for selectively inputting said sensor signals to said arithmetic circuit. 
     
     
       17. A method for controlling an internal combustion engine comprising; detecting engine operating conditions including detecting engine intake vacuum and atmospheric air pressure alternatively at a given timing by selectiveoly applying said engine vacuum and said atmospheric air pressure to a sensor;   determining a basic value of exhaust gas recirculation rate for recirculating exhaust gas into the engine cylinders based on engine operating conditions including said intake vacuum; and   correcting the determined basic exhaust gas recirculation rate depending on a correction value determined according to said atmospheric air pressure;   controlling the exhaust gas recirculation rate depending upon the corrected value.